The causes of most Parkinson?s disease (PD) cases are unknown -?? ~90% are ?sporadic?, ~10% are attributed to inheritance. Environmental factors, including pesticides and solvents, have long been suspected, but no toxicanthasbeenconvincinglyidentified.Mostcasesarethoughttoarisefromgene-??environmentinteractions. A specific example is leucine-??rich repeated kinase 2 (LRRK2), a large multi-??domain protein with an unknown endogenous function. Numerous LRRK2 mutations cause PD. However, incomplete penetrance in humans and heightened sensitivity to dopaminergic (DA) neuron toxicants in animals expressing mutations suggest the importance of gene-??environment interactions. Mounting data from the Cannon laboratory and others suggests that heterocyclic aromatic amines (HAAs) are neurotoxic and associated with neurodegenerative diseases, including PD. HAAs have been primarily investigated as carcinogens in laboratory animals and as potential human carcinogens. HAAs are formed during high temperature meat and poultry cooking. Thus, chronic HAA exposure through diet may be much more common and occur at higher levels than for many environmental toxicants. This proposal tests the hypothesis that: 2-??Amino-??1?methyl-??6-??phenylimidazo[4,5-?? b]pyridine(PhIP),themostmassabundantHAAincookedmeatsandpoultry,exhibitsselectivedopaminergic neurotoxicity by a newly proposed mechanism of neurotoxic action through N-??hydroxylation,ametabolitein commonwithPhIP?smediatedgenotoxicity.OurdatasuggeststhatmechanisticstudiesonPhIPneurotoxicity are critical to understanding a potential role in PD. The major goals of this proposal are to: 1) Characterize PhIP-??mediated neurotoxicity in vivo; 2) Determine if PhIP exposure potentiates pathology in animals expressingmutated(G2019S)LRRK2(themostcommongeneticcauseofPD);3)Identifykeymechanism(s)of PhIP-??mediated DA-??selective neurotoxicity through examination of whether N-??hydroxylation is a key pathogenic event, and by assessing the propensity of N-??oxidized PhIP metabolites to broadly form adducts with major biomolecules. Modifications and adduct formation in specific PD-??implicated proteins will also be examined. Success of this project will lead to several major advances. 1) Identification of a possible causative factor:PhIPisacommontoxicantproducedincookedmeatsandmaybeconsumedinhigherdosesthanrarely encounteredknownDAtoxicants;2)Creationofanewgene-??environmentinteractionmodelutilizingthemost common PD causing-??mutation and a compound to which humans are widely exposed; 3) New PD mechanisms: mechanistic studies would likely identify novel pathogenic pathways that may be therapeutic targets; 4) Prompt follow-??up epidemiological and biomarker studies. In summary, using both in vivo and in vitrosystems,wewillcarefullycharacterizePhIP-??inducedneurodegenerationandidentifymechanismsofDA neurotoxicity. If PhIP exposure is proven to have a causative role in PD, then recommendations can be providedtothepublicbecausePhIPexposurecanbemitigatedbychangesincookingmethods.